Rotary wafer type electrical switch



April 6, 1965 R. STENGL ROTARY WAFER TYPE ELECTRICAL SWITCH Original Filed 001:. 26, 1960 2 Sheets-Sheet 1 INVENTOR.

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A ril 6, 1965 R. STENGL ROTARY WAFER TYPE ELECTRICAL SWITCH 2 Sheets-Sheet 2 Original Filed Oct. 26, 1960 NN hw IN VEN TOR.

fM 52' BY- 0/4022, jj/forzlwyef; we)? United States Patent ROTARY WAFER TYPE ELECTRICAL SWHTCH Robert tengl, Morton Grove, Iii, assignor to dtandard Grigshy End, a corporation of Delaware firiginal application Oct. 26, I960, Ser. No. 65,182. Divided and this application Dec. 22, 19-51, Ser.

12 (llaims. (til. Ztttl11) This invention relate-s to an electrical switch and a' method of manufacturing electrical switches, and more particularly to an improved rotary electrical switch of the wafer type and a method of manufacturing wafer switches which conserves material, reduces costs and results in mechanicallyand electrically improved devices.

This application is a division of the prior application of Robert Stengl, Ser. No. 65,182, filed ()ctober 2 6, 1960.

In the electrical industry, rotary switches of the wafer type are extremely common. They are widely used in electronic equipment where multiple positions are required in sequencing, programing, channel selection, and the like. One very common use of such switches is in multiple channel television tuners. Typically, 3 or 4 wafer switches are stacked together and supported in spaced parallel relationship with a common operating shaft extending centrally therethrough. A single knob, usually designated the channel selector, rotates the central portion or rotor of each wafer switch to selectively tune various radio frequency circuits in the television receiver. In a typical design these circuits may include an antenna circuit, an R-F amplifier, a mixer input, and a conversion oscillator. Heretofore the rotary wafer switches employed in television tuners and in similar applications have been relatively large and costly to manufacture. While it is desirable to minimize the stray electrical effects produced by the switch components, prior art devices have often exhibited large and unpredictable stray effects.

It is, therefore, one object of this invention to provide a mechanically improved wafer switch of substantially reduced size.

It is still another object of this invention to provide a small wafer switch having improved structural rigidity, good bearing characteristics for the switch rotor, and a wafer switch in which the plurality of spaced contacts do not support the rotor and are not employed as a structural element in the switch.

It is still another object of this invention to provide an improved rotary wafer switch having a minimum amount of stray electrical effects and, more particularly, having minimum intercontact and stray capacitance.

A further object is the creation of an electrically improved switch in which positive low impedance contact is produced at all times between the Various switch elements.

It is a further object of this invention to provide an improved miniature electrical switch having means incorporated therein for tuning certain of the switch components which then function also as components of a tuned circuit.

Another object of this invention is the provision of improved assembly techniques and processes for the manufacture of wafer switches. The assembly process of this invention saves substantial quantities of raw material, enables a reduction in the size of the ultimate product, is well adapted to automation, requires minimum handling of the component parts, and greatly reduces defective products and Waste materials.

Further and additional objects of this invention will become manifest from a consideration of this specification, the accompanying drawings and the appended claims.

In one form of the invention a miniature wafer switch for use in television receivers is provided in which a circular pattern of electrical contacts is initially connected together by an inner ring and assembled onto an insulating stator. Thereafter the removal of the supporting ring by the passage of a metal punching tool through a central aperture in the stator produces a completed multicontact stator assembly. The supporting ring and the inner portions of the various contacts are formed with offset portions whereby they are spaced from the plane of the stator to define an annular recess which receives radial fingers extending outwardly from the associated rotor. The fingers of the rotor are so shaped and spaced that they pass between the various contacts and produce bear ing surfaces against the periphery of the central aperture in the stator. A retaining ring is then secured to the 0pposite side of the rotor whereby the peripheral portions of the stator defining the contra aperture are entrapped between the fingers and the retaining means. Thus, the electrical contacts do not support the rotor in any way and are not required to function as mechanical elements in addition to serving their electrical purposes.

For a more complete understanding of the invention, reference will now be made to the accompanying drawings, wherein:

FIGURE 1 is a perspective view of a wafer switch normally forming a part of a television tuner and illustrating one embodiment of the article provided by this invention;

FIG. 2 is a top plan view of the wafer switch of FIG. 1; FIG. 3 is a sectional view of the wafer switch of FIG. 1 taken on the line 33 of FIG. 2;

FIG. 4 is an exploded view of the stator and preformed contact assembly during one step of the manufacturing process of this invention;

FIG. 5 illustrates the parts shown in FIG. 4 but in assembled relationship;

FIG. 6 is an exploded view illustrating another step in the manufacturing process and incorporating the subassembly of FIG. 5 in an inverted position, and

FIG. 7 is a cross-sectional view of the rotor taken on the line 77 of FIG. 6.

Referring now to the drawings and more particularly to FIGS. 1, 2 and 3, a wafer switch 10, having a stator 12 and rotor 14', is illustrated. The stator 12 and rotor 14- are made of an insulating material, such as a phenol sheet or molded plastics, such as polystyrene or polyethylene. Individually secured to the stator 12 are a plurality of electrically isolated contacts 16. A further group of contacts 18 individually secured to stator 12, but electrically interconnected, are provided to complete a uniform circular pattern with contacts 16.

Threaded elements such as screws 20, are disposed 7 between the electrically isolated contacts 16 and adjacent to the b ight portions of the interconnected contacts 18. The screws 24 which are preferably made of brass, constitute tuning elements where desired in high frequency electrical circuits. In particular, in a TV tuner the upper or high frequency channels are selected by engaging one of the interconnected contacts 18 and the requency involved is in the order of 200 megacycles. At such frequencies the U-shaped portions interconnecting the contacts 18 form the tunable components of a tuned circuit incorporated in the wafer switch. Thus, between each of the contacts 18 the fiat metallic U-shaped portion 22 defines an inductive element. The brass screws 20, passing through the stator adjacent to but electrically isolated from the tunable element, varies the inductance of that element and determines the frequency of the tuned circuit when the switch is used in conjunction with a predetermined capacitance. For this reason,

it is important to minimize the stray and unpredictable capacitance effects which sometimes occur between switch elements. The instant invention accomplishes cameos this in a unique manner by providing maximum space between the conductive components. Furthermore, air constitutes the intermediate medium wherever possible to avoid the larger capacitance effects produced by the higher dielectric rotor and stator materials.

Each contact 16 has a terminal portion 24 which passes through an appropriate small aperture in stator 12. The contacts 16 and 18 are preferably secured in the stator 12 by a staking operation. vides the electrical connection for all of the interconnected contacts 18. The rotor 14, as best shown in FIG. 7, has a central aperture 28 with lceyways 30 to receive a keyed drive shaft. The periphery of rotor 14 has radial fingers 32 adjacent one surface thereof and narrow peripheral ribs 34 aligned with fingers 32 and disposed on the peripheral edge of the rotor. The ribs and fingers are so proportioned and spaced that they pass freely through the spaces between adjacent contacts 16 and 1%. The radial inward portions 36 of contacts 16 and 18 are ofifset from the plane of stator 12 to de- :fine an annular recess. Thus, when the rotor is in position the radial fingers 32 occupy the recess 3%.

The rotor is retained in position by a conductive ring 46 which is secured to the side of the rotor opposite fingers 32 by rivets 42. Also, secured to rotor 14 by rivets 4-2 is a conductive wiper 44 Wiper 44 has an arcuate portion 46 partially surrounding the central rotor aperture 28 and receiving .tWo of the rivets 4,2. Extending radially outward from the arcuate portion 46 are a pair of wiper arms 45, which engage any one of the contacts 16 or 18 selectively depending upon the relative rotary position of rotor 14 and stator 12. Wiper arms 46 have somewhat cupped end portions 50 to produce more positive and low resistant contact with the individual contacts 16 and 18.

A similar pick-off wiper 66 is secured in stator 12 A single terminal 26 proand continuously engages ring as for completing the selected circuit. The steps in the manufacture of this switch are best illustrated in FIGS. 4, 5 and 6. In FIG. 4 a preformed contact assembly 52 includes a central supporting ring 5 1- and all of the preformed contacts 16 and 18. The supporting ring 54 and radially inward contact portions 36 are in a plane slightly removed from the plane of the remainder of the preform 52 and connected thereto by the inclined intermediate portions 56, thus defining annular recess 38. Each contact 16 and contact 18 has a terminal portion 24 or 26 formed a normally to the stator plane with an arcuate solder lug 5S. Adjacent to solder lug 58 small shoulders 66 are defined, and spaced from shoulders 60 are transverse clamping studs 62. As is clear in FIG. 4 the stator 12 has preformed apertures 65 to receive the solder lugs 24 and has preformed adjacent slots 67 to receive the clamping studs 62. Thus, when the preform 52 is placed in overlying relationship on stator 12, a sub-assembly, as shown in FIG. 5, results, A staking tool is then applied which deforms or splits the clamping studs 62 and the shoulders 66, whereby each contact 16 and the contacts 18 are permanently located in the stator 12.

At this stage, .by means of an applied punch, the supporting ring 54 is removed, thereby providing an opening through which the rotor 14 is received.

The next step in assembly is illustrated in FIG. 6 where the rotor 14, wiper 44 and retaining ring 4-6 are shown in an exploded view. The rotor 14 is dropped into place from the position shown in FiG. 6 with the radial fingers 32 nesting between the contacts 16 and 1d and coming to rest on the surface of stator 12. The wiper 4A- is then placed on the rotor 14 with the apertures aligned and with the wiper arms 4% entrapping one of the contacts 16 or 18. Three rivets are then passed through apertures in the wiper 4,4, rotor 14 andretaining ring it), with the retaining ring against the opposite face of stator 12. When the rivets are deformed a permanent assembly results with selective contact between the wiper arms 48 and any one of the contacts 16 or 153. The radial ribs 34 bear against the inner edge 64, which defines the central aperture in stator 12 and thus a restrained and accurate but relatively low friction rotary movement is provided. This is true even though the the inner edges of contacts 16 and 18 may fall somewhat within the cylinder defined by the central aperture. The pick-off wiper 66 is then secured to stator 12 by rivet 67 and has spaced arms 66 which continuously engage collector ring 4d.

This combination of wiper and contacts provides a continuous connection to a circuit associated with one of the preselected contacts 16 or 13, as will be understood readily from the foregoing description and the drawings. An electrical circuit is at all times completed through the rotary switch from the pick-off wiper 66 through the retaining ring as, the rivets 42, the wiper 44, and one of the contacts 16 or 13. The contacts 18 are connected together through inductive portions 22 and a single terminal 26 connects the contacts 18 to other circuit components in a tuned circuit. Each of the contacts 16 is individually connected through an associated circuit component, such as a predetermined inductance coil to the same tuned circuit. Thus, by turning the rotor 14- any one of thirteen predetermined positions may be selected.

A detent mechanism is normally associated with the knob and shaft employed with sucha wafer switch to positively determine the 13 selected positions. However, as these are conventional elements, they are not illustrated in the instant drawings. Also, while theparticular switch illustrated has 13 positions corresponding :to the 13 VHF television channels, it will be immediately apparent that the wafer switch and method of manufacture provided by this invention have many applications irrespective of the number of contacts employed or associate circuit components. One particular advan- .tage of the instant invention is the fact that the contacts do not support the rotor in position and thus a full set of contacts formed completely about the periphcry of the central aperture is not required. If desired in a particular use, only two or three contacts, either immediately adjacent to one another or distributed about the periphery, might be used.

Without further elaboration, the foregoing will so fully explain the character of my invention that others may, by applying current knowledge, readily adapt the same for use under varying condtions of service, while retaining certain features which may properly be said to constitute the essential items of novelty involved, which items are intended to be defined and secured to me by the following claims.

I claim: a V

1. A rotary switch comprising generally planar stator means of insulating material having a central aperture, rotor means of insulating material having a diameter less than the diameter of said central aperture, a plurality of electrical contacts circumferentially disposed in spaced relationship about said wntral aperture, the radially inward portions thereof extending radially to the edge of said aperture and being spaced from the plane of said stator means to define an annular recess, radial protuberances extending outwardly from said rotor means and engaging said stator means adjacent said central aperture and intermediate said stator means and said electrical contacts in said annular recess, and retaining means secured to said rotor means whereby the peripheral portion of said stator means adjacent said central aperture is entrapped between said retaining means and said protuberanoes.

2. A rotary switch comprising generally planar stator means of insulating material having a central aperture,

rotor means of insulating material having a diameter less than the diameter of said central aperture, a plurality of electrical contacts circumferentially disposed in spaced relationship about said central aperture, the radially inward portions thereof extending radially to the edge of said aperture and being spaced from the plane of said stator means to define an annular recess, radial protuberances extending outwardly from said rotor means and engaging said stator means adjacent said central aperture and intermediate said stator means and said electrical contcts in said annular recess, electrical wiper means secured to said rotor means and selectively engaging said electrical contacts, the contact engaged being dependent upon the relative rotary positions of said stator means and said rotor means, and retaining ring means secured to said rotor means whereby the peripheral portion of said stator means adjacent said central aperture is entrapped between said ring and said protuberances.

3. A rotary switch comprising a generally planar stator means of insulating material having a central aperture, rotor means of insulating material having a diam eter less than the diameter of said central aperture, a plurality of electrical contacts circumferentially disposed in spaced relationship about said central aperture, the radially inward portions thereof extending radially to the edge of said aperture and being spaced from the plane of said stator'means to define an annular recess, radial fingers extending outwardly from said rotor means and engaging said stator means adjacent said central aperture and intermediate said stator means and said electrical contacts in said annular recess, electrical wiper means secured to said rotor means and selectively engaging said electrical contacts, the contact engaged being dependent upon the relative rotary positions of said stator means and said rotor means, conductive retaining ring means in electrical communication with said wiper means and secured to said rotor means whereby the peripheral portion of said stator means adjacent said central aperture is entrapped between said ring and said fingers, and electrical contact means secured to said stator and in continuous electrical contact with said ring means.

4. A rotary switch comprising a generally planar stator means of insulating material having a central aperture, rotor means of insulating material having a diameter less than the diameter of said central aperture, a plurality of electrical contacts circumterentially disposed in spaced relationship about said central aperture, the radially inward portions thereof extending radially to the edge of said aperture and being spaced from the plane of said stator means to define an annular recess, radial fingers extending outwardly from said rotor means and engaging said stator means adjacent said central aperture and intermediate said stator means and said electrical contacts in said annular recess, ribs formed on the peripheral edge of said rotor means and engageable with the inner edge of said stator means defining said central aperture, electrical wiper means secured to said rotor means and selectively engaging said electrical contacts, the contact engaged being dependent upon the relative rotary positions of said stator means and said rotor means, conductive retaining ring means in electrical communication with said wiper means and secured to said rotor means whereby the peripheral portion of said stator means adjacent said central aperture is entrapped between said ring and said fingers, and electrical contact means secured to said stator and in continuous electrical contact with said ring means.

5. A rotary switch comprising a generally planar stator means of insulating material having a central aperture, rotor means of insulating material having a diameter less than the diameter of said central aperture, a plurality of electrical contacts circumfereutially disposed in spaced relationship about said central aperture, the radially inward portions thereof extending radially to the edge of said aperture and being spaced from the plane of said stator means to define an annular recess, radial fingers extending outwardly from said rotor means and engaging said stator means adjacent said central aperture and intermediate said stator means and said electrical contacts in said annular recess, said radial fingers being appropriately disposed about the periphery of said rotor means and of predetermined width less than the spacing between said electrical contacts whereby said fingers align with said spaces, electrical wiper means secured to said rotor means and selectively engaging said electrical contacts, the contact engaged being dependent upon the relative rotary positions of said stator means and said rotor means, conductive retaining ring means in electrical communication with said wiper means and secured to said rotor means whereby the peripheral portion of said stator means adjacent said central aperture is entrapped between said ring and said fingers, and electrical contact means secured to said stator and in continuous electrical contact with said ring means.

6. A television tuner switch comprising a planar stator of insulating material having a central aperture, a plurality of electrical contacts uniformly disposed on said stator circumferentially about said central apertures, a plurality of said electrical contacts being formed in a single sheet and interconnected, the radially inward portions of said contacts extending radially to the edge of said aperture and being spaced from the plane of said stator means to define an annular recess, rotor means of insulating material having a diameter less than the diameter of said central aperture and having a plurality of narrow ribs on the peripheral edge to engage the edge of said stator, said rotor means also having a plurality of uniformly spaced radially extending fingers narrower than the spaces between said electrical contacts and aligned therewith, and retaining means for rotatably securing said rotor means within said central aperture with said radial fingers disposed in said annular recess.

7. A television tuner switch comprising a planar stator of insulating material having a central aperture, a plurality of electrical contacts uniformly disposed on said stator circumferentially about said central apertures, a plurality of said electrical contacts being formed in a single sheet and interconnected by bifurcated radially outward portions, the radially inward portions extending radially to the edge of said aperture and being spaced from the plane of said stator to define an annular recess, conductive means movable in said stator in spaced, isolated relationship to the bight portions of said bifurcated contacts, rotor means of insulating material having a diameter less than the diameter of said central aperture and having a plurality of narrow ribs on the peripheral edge to engage the edge of said stator, said rotor means also having a plurality of uniformly spaced radially extending fingers aligned with said ribs and narrower than the spaces between said electrical contacts and aligned therewith, conductive retaining means for rotatably securing said rotor means within said central aperture with said radial fingers disposed in said annular recess, and electrical contact means mounted on said stator and slidably engaging said retaining means.

8. A rotary switch comprising a planar stator of insulating material having a central aperture, a plurality of electrical contacts disposed on said stator surrounding said central aperture, the radially inward portions of said electrical contacts extending radially to the edge of said aperture and being spaced from the plane of said stator to define an annular recess, and rotor means of insulating material having peripheral portions thereof adjacent the edge of said aperture and disposed in said annular recess.

9. A rotary switch comprising a planar stator of insulating material having a central aperture, a plurality of electrical contacts disposed on said stator surrounding said central aperture, the radially inward portions of said electrical contacts extending radially to the edge of said aperture and being spaced from the plane of said stator to define an annular recess, rotor means of insulating material having peripheral portions thereof adjacent the edge of said aperture and disposed in said annular recess, a conductive collector ring secured to said rotor means, a

conductive wiper secured to said' rotor means and selectively engaging said electrical contacts, and an electricalv contact secured to said stator and engaging said collector ring. 7

10. A rotary switch comprising a planar stator of insulating material having a central aperture, a plurality of electrical contacts disposed on said stator surrounding said central aperture, the radially inward portions of said electrical contacts adjacent the edge of said aperture and being spaced from the plane of said stator to define an annular recess, rotor means of insulating material having peripheral portions thereof adjacent the edge of said aperture and disposed in said annular recess, said rotor means having a portion fitted Within said central aperture to maintain said rotor means in generally axial alignment with saidcentral aperture, a conductive collector ring secured to said rotor means, a conductive wiper secured to said rotor means and selectively engaging said electrical contacts, and an electrical contact secured to said stator and engaging said collector ring.

11. A rotary switch comprising a planar stator of insulating material having a central aperture, a plurality of electrical contacts disposed on said stator surrounding said central aperture, the radially inward portions of said electrical contacts adjacent the edge of said aperture and being spaced from the plane of said stator to define an annular recess, rotor means of insulating material having peripheral portions thereof adjacent the edge of said aperture and disposed in said annular recess, said portion comprising radial fingers narrower than the spaces between said electrical contacts, a conductive collector ring secured to said rotor means, a conductive wiper secured to said rotor means and selectively engaging said electrical contacts and an electrical contact secured to said said central aperture, the radially inward portions of said electrical contacts adjacent the'edge of said aperture and being spaced from the plane of said stator to define an annular recess, rotor means of insulating material having peripheral portions thereof adjacent the edge of said aperture and disposed in said annular recess, said portion comprising radial fingers narrower than the spaces between said electrical contacts, said rotor means having a portion disposed within said central aperture and having ribs formed thereon for bearing engagement With the edge of said stator defining the central aperture, a conductive collector ring secured to said rotor means, a conductive wiper secured to said rotor means and selectively engaging said electrical contacts, and an electrical contact secured to said stator and engaging said collector ring.

References Cited by the Examiner -UNITED STATES PATENTS 2,576,836 11/51 Hilsinger 200-14 2,870,275 1/59 Gelzer ZOO-15 2,900,462 18/59 Thomas et a1. 200-15 FOREIGN PATENTS 7 318,605 2/57 Switzerland.

BERNARD A. 'GILHEANY, Primary Exaniiner. 

1. A ROTARY SWITCH COMPRISING GENERALLY PLANAR STATOR MEANS OF INSULATING MATERIAL HAVING A CENTRAL APERTURE ROTOR MEANS OF INSULATING MATERIAL HAVING A DIAMETER LESS THAN THE DIAMETER OF SAID CENTRAL APERTURE, A PLURALITY OF ELECTRICAL CONTACTS CIRCUMFERENTIALLY DISPOSED IN SPACED RELATIONSHIP ABOUT SAID CENTRAL APERTURE, THE RADIALLY INWARD PORTIONS THEREOF EXTENDING RADIALLY TO THE EDGE OF SAID APERTURE AND BEING SPACED FROM THE PLANE OF SAID STATOR MEANS TO DEFINE AN ANNULAR RECESS, RADIAL PROTUBERANCES EXTENDING OUTWARDLY FROM SAID ROTOR MEANS AND ENGAGING SAID STATOR MEANS ADJACENT SAID CENTRAL APER- 